The present disclosure describes systems and techniques relating to pilot tones used in communication systems.
Orthogonal frequency division modulation (OFDM) is a modulation technique for communications which splits a data stream into multiple data substreams. Such data substreams are sent over different OFDM subcarriers, which can be referred to as frequency tones or simply tones.
Wireless networks can use OFDM to transmit and receive signals. Examples of OFDM-based systems include wireless local area networks (WLANs, e.g., WiFi networks) such as those defined in the Institute of Electrical and Electronics Engineers (IEEE) wireless communications standards, e.g., IEEE 802.11a, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac. Some wireless networks use a single-in-single-out (SISO) communication approach, where each wireless communication device uses a single antenna. Other wireless networks use a multiple-in-multiple-out (MIMO) communication approach, where a wireless communication device uses multiple transmit antennas and multiple receive antennas. WLANs, such as ones based on the IEEE 802.11n or IEEE 802.11ac standards, can use OFDM and MIMO.